How do I check my Audi oil levels and what should I do if they're low?

I am a new Audi owner and want to make sure I am properly maintaining my vehicle. How can I check my oil levels and what steps should I take if they are low?

To check the oil levels in your Audi, make sure the engine is off and locate the dipstick, usually indicated by a yellow handle. Pull out the dipstick, wipe it clean with a cloth, reinsert it, and then pull it out again. The oil level should be between the two indicators on the dipstick.